Adjustments for Missed Doses

Example of immunotherapy dose adjustments for unscheduled gaps in allergen immunotherapy injection intervals during build-up phase.

Time after missed injection during build-up phase---	Adjustment to dose
1-7 days	Continue as scheduled
8-13 days	Repeat previous dose
14-21 days	Reduce previous dose 25%
21-28 days	Reduce previous dose 50%------

Note

A similar dose reduction protocol should be developed for gaps in maintenance immunotherapy.
The immunotherapy dose and schedule, as well as the benefits and risks of continuing immunotherapy, should be evaluated after any immunotherapy-induced systemic reaction. After a severe systemic reaction, careful evaluation by the prescribing physician is recommended. For some patients, the immunotherapy maintenance dose might need to be reduced because of repeated systemic reactions to immunotherapy injections. The decision to continue immunotherapy should be re-evaluated after severe or repeated systemic reactions to allergen immunotherapy extracts.

2 large prospective studies showed no increase in the incidence of systemic reactions during the pollen seasons for which the patient was receiving treatment, suggesting that reductions in dose during the pollen seasons are not necessary

Postpone the injection in the presence of any wheezing or signifacnt recent increase in symptoms (particularly of wheezing), or an intercurrent illness
Do not increase the dose if the interval was 3-4 weeks since the last dose or if the last dose caused a local swelling up to a quarter (25 cents) in diameter. Next dose may be increased per schedule.
Reduce the dose to 1/2 if there was local swelling more than a quarter size.
Reduce the dose to 1/10 if there was a systemic reaction.
During periods or seasons of increased exposure to offending allergens, the dose may need to be reduced by 25-75%
If the interval since last injection was:

Time after missed injection during build-up phase---	Adjustment to dose
5-7 weeks	Reduce the dose to 1/2 then build up by weekly increments of 0.05 mL
8-12 weeks	Reduce the dose to 1/4 then build up by weekly increments of 0.05 mL
3-6 months	Reduce the dose to 1/10 then build up by weekly increments of 0.05 mL
6-12 months	Reduce the dose to 1/100 then build up by weekly increments of 0.05 mL
1 year or more	The patient should be re-evaluated and skin testing may need to be repeated

Adjustments for New Vial

For lot changes from the same manufacturer, the physician can consider decreasing the injection dose by 50% to 90% of the previous dose.
For changes in manufacturer and nonstandardized extracts, a greater decrease in dose might be necessary.

Whenever a patient on maintenance recieves a new vial of "full strength" extract, begin with 1/2 of the last dose, then build up the dose by increments of 0.05 mL until maintenace dose is reached, which may be different from the previous maintenance dose.

It is the custom in our practice for patients receiving monthly injections who require a new vial to decrease the dose by 50% and build to maintenance with weekly injections requiring 5 weeks to return to maintenance level. Thus we would decrease the dose from 0.5 ml to 0.25 ml, and build back by 0.05 increments until 0.5 ml is reached. We then return to monthly injections.